Various wireless access technologies have been proposed or implemented to enable mobile stations to perform communications with other mobile stations or with wired terminals coupled to wired networks. Examples of wireless access technologies include GSM (Global System for Mobile communications) or UMTS (Universal Mobile Telecommunications System) technologies, defined by the Third Generation Partnership Project (3GPP); CDMA 2000 (Code Division Multiple Access 2000) technologies, defined by 3GPP2; or other wireless access technologies. The CDMA 2000 family of wireless access technologies includes the 1xRTT wireless access technology (generally used to perform circuit-switched communications), and the 1xEV-DO (or EV-DO) wireless access technology (used for communication of packet data and defined by the High Rate Packet Data (HRPD) specification, also known as the IS-856 specification).
More recently, further development of the 3GPP standards have lead to the 3GPP LTE (Long Term Evolution) wireless access technology. The LTE technology is the next generation enhancement of the UMTS technology to provide improved data speeds, reduced latency, and others.
Certain mobile stations are able to support multiple different types of wireless access technologies. For example, a mobile station can support both the LTE wireless access technology as well as the EV-DO wireless access technology. Such a mobile station can move between an LTE wireless access network and an EV-DO wireless access network.
When performing active handover of a mobile station between different wireless access networks (such as between an LTE wireless access network and an EV-DO wireless access network), conventional standards may not support the handling of certain types of messages that are sent from the access network to the mobile station during the handover process.